What are Evidence and Gap Maps?

EGMs are systematic and visual presentations of the available evidence for a particular sector or sub-sector. Evidence is usually represented in a row and column matrix representing intervention outcomes for effectiveness studies or regions and economics for regional evaluations. The primary dimensions of the map are rows and columns. Secondary dimensions of the map for included studies are often referred to as filters.

What does the map include?

This EGM includes 434 economic and financial evaluations of the interventions targeted at improving women’s, children’s, and adolescent's health (WCAH) in low-and-middle-income countries.

How to read the map:

For each intervention-outcome cell, a bubble indicates the included economic evaluation. As indicated by the bubbles' colour, the economic evaluations' quality is represented as red for low quality, orange for medium quality, and green for high quality. The quality has been assessed using Drummond Checklist. The bubble size represents the volume of evidence available for a particular intervention subcategory and outcome subcategory.

Thus, a larger bubble size for specific cells indicates a greater number of studies exist. In contrast, smaller bubbles refer to a relative lack of studies for a specific intervention and outcome subcategory. However, a single study might appear under more than one cell, as it may fall under more than one intervention and outcome combination.

This EGM includes several filters related to geographic location, population, intervention and outcome characteristics. The users may select one or more filters to see the corresponding studies along the matrix.

For example, suppose one is interested in finding economic and financial evaluations targeted at children under 5 years and conducted in South Asia. In that case, the studies with these characteristics may be retrieved by selecting the required filters, such as South Asia as the region (geographic), and children under 5 years as the target group of intervention. The map lets users see the bibliographic information and links studies, mostly via URLs or DOIs.

The map has four style versions available: bubble, heat, donut and mosaic. These are self-explanatory and can be accessed by clicking -> Filters (top left of map), and selecting your preferred Style. Clicking on a cell provides a list of systematic reviews corresponding to the intervention and outcome for that cell. Click on a study in the list to access publication details, and the URL to access the study itself.